Prosthetic heart valves have been used to replace defective human valves in patients. A prosthetic valve generally includes a sewing ring or suture cuff that may be attached to and/or extend around a valve member. The sewing ring may be made from a biocompatible fabric and/or other material through which a needle and suture may pass. The sewing ring may be part of a single piece prosthetic valve, or may be part of a multiple piece prosthetic valve assembly.
In a typical aortic valve replacement procedure, the aorta may be incised and the defective valve leaflets removed, leaving a desired placement site that may include a fibrous tissue layer or tissue annulus. Needles carrying sutures may be directed through the fibrous tissue or desired placement site within the tissue annulus to form an array of sutures. Free ends of the sutures may be extended out of the thoracic cavity and laid, spaced apart, on the patient's body.
The needles and sutures may then be threaded individually through a sewing ring, typically delivering between ten and twenty (12-20) sutures through the sewing ring. Once the sutures have been directed through the sewing ring, the sutures may be pulled up taught and the sewing ring may be slid over the sutures or “parachuted” down into place adjacent the placement site tissue. The sewing ring may then be secured in place by knot tying knots in the sutures. This procedure is time consuming as doctors often use three to ten knots per suture.
If the sewing ring is separate from a valve member of a multiple component prosthesis, the valve member may be introduced into the placement site, and secured to the sewing ring. The sutures may be tied, not only to secure the sewing ring to the biological mass and, but to secure the valve member to the sewing ring (and consequently, to the tissue annulus).
During heart valve replacement procedures, the patient may be on cardiopulmonary bypass (CPB), which may reduce the patient's oxygen level and/or create non-physiological blood flow dynamics. The longer a patient is on CPB, the greater the risk for long-term or even permanent health damage. Existing suturing techniques extend the duration of CPB and, consequently, increase the health risks due to the patient. Furthermore, the fixturing force created by suturing varies significantly from suture to suture, even for the same medical professional.
Sewing rings can also be tedious and time consuming to secure to a valve orifice. To assemble multiple component heart valves, for example, one component has to be sewn into another in vivo, resulting in a complex and time consuming process. The complexity of the procedure also provides a greater opportunity for mistakes and requires a patient to be on cardiopulmonary bypass for a lengthy period.